ANALYTICAL AND CLINICAL-PERFORMANCE OF IMPROVED ABBOTT IMX CA-125 ASSAY - COMPARISON WITH ABBOTT CA-125 RIA

We compared the improved Abbott IMx cancer antigen (CA) 125 assay (cat , no. 7A89) with the Abbott CA 125 RIA. Serum specimens were from heal thy perimenopausal women (n = 124) and from patients with benign gynec ologic and nongynecologic diseases (n = 124), ovarian carcinoma (n = 1 04), or other malignancies (n = 193). The IMx assay detected as little as 0.193 kAU/L CA 125 (AU = arbitrary Abbott unit), demonstrated up t o 29% overestimation upon serum dilution, low within-assay (2.7-5.6%) and between-assay (4.8-8.2%) CVs, and no high-dose hook effect less th an or equal to 46 000 kAU/L nor influence from human anti-mouse antibo dies in serum of women injected with OC 125 F(ab')(2). Values by IMx w ere 20% lower than by RIA for healthy perimenopausal women (n = 100; I Mx = 0.80 RIA - 2.5 kAU/L), and at least 50% higher for those with ben ign or malignant ovarian disorders at concentrations <100 kAU/L. Recei ver-operating characteristic (ROC) curve analysis of ovarian neoplasma vs perimenopausal controls indicated a gain of specificity and sensit ivity with the improved IMx assay over the RIA, but ROC performance wa s the same with either assay if patients with benign ovarian disorders were used as controls.